Filter bag



FIG. 1 is a front view of a filter bag showing our new design;

FIG. 2 is a right side elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is an unfolded flat view thereof.

The features shown in broken lines depict environmental subject matter only and form no part of the claimed design. 

CLAIM The ornamental design for a filter bag, as shown and described. 